The invention relates to a method for winding an electrical machine, which contains a rotation axis and a base body with two axial end faces and with slots for holding electrical conductors of a winding system, with the slots each having a slot end opening on the end faces. The invention also relates to an auxiliary winding body for carrying out the method.
A method such as this is used, for example, for winding a base body which is in the form of a stator or laminated stator core. Recently, the winding process has been carried out using so-called needle winders, with a winding nozzle of the needle winder inserting an electrical conductor in the interior of a stator bore into one of the slots and moving forwards in the axial direction, that is to say in the direction of the rotation axis. On the end face, the winding nozzle (=needle) is first of all also moved slightly outwards in the axial direction. The laminated stator core is then rotated about the rotation axis until the slot end opening of that slot in which the electrical conductor is passed back in the opposite direction within the stator bore appears at the level of the winding nozzle. The process is carried out in mirror-image form on the opposite end face. This is repeated as appropriate for the desired number of turns, so that end windings are formed on both end faces.
The winding system may have a plurality of winding elements, which are introduced into the laminated stator core successively using the described method. In this case, the deflection path length on the end faces for winding elements which are introduced later is greater than that for the winding elements manufactured first. In consequence, the mean coil lengths of the individual winding elements differ from one another. Furthermore, more material is used for the winding elements which are introduced later, as a result of which the individual winding elements may also have electrical resistance differences.
These undesirable consequences can be compensated for by means of controlled catching elements on both end faces. However, their use is highly complex and slows down the cycle time of the winding process.
Furthermore, the deflection process of the electrical conductor in the area of the end faces can result in a high tensile strength, which can lead to an unacceptable strain and, resulting from this, in a constriction in the cross section of the electrical conductor. Furthermore, the electrical conductor may also be damaged.